ntkr3
Introduction
NTRK3 (Neurotrophic Receptor Tyrosine Kinase 3) encodes TrkC (Tropomyosin receptor kinase C), the primary high-affinity receptor for neurotrophin-3 (NT-3). TrkC is a receptor tyrosine kinase crucial for neuronal development, synapse formation, and neuronal survival. During development, NT-3/TrkC signaling promotes the differentiation and survival of specific neuronal populations, particularly in the peripheral nervous system and certain brain regions. While less studied in neurodegeneration than TrkA and TrkB, the NT-3/TrkC pathway has important roles in the adult brain and may have protective effects in aging and disease. Additionally, NTRK3 gene fusions are driver events in several human cancers, making TrkC a clinically important therapeutic target.
<div class="infobox infobox-gene">
<div class="infobox-header">NTRK3</div>
<div class="infobox-row"><span class="infobox-label">Gene Symbol</span><span class="infobox-value">NTRK3</span></div>
<div class="infobox-row"><span class="infobox-label">Full Name</span><span class="infobox-value">Neurotrophic Receptor Tyrosine Kinase 3 (TrkC)</span></div>
<div class="infobox-row"><span class="infobox-label">Chromosomal Location</span><span class="infobox-value">15q25.3</span></div>
<div class="infobox-row"><span class="infobox-label">NCBI Gene ID</span><span class="infobox-value"><a href="https://www.ncbi.nlm.nih.gov/gene/4916" target="_blank">4916</a></span></div>
<div class="infobox-row"><span class="infobox-label">OMIM</span><span class="infobox-value"><a href="https://www.omim.org/entry/191316" target="_blank">191316</a></span></div>
<div class="infobox-row"><span class="infobox-label">Ensembl ID</span><span class="infobox-value"><a href="https://www.ensembl.org/Homo_sapiens/Gene/Summary?g=ENSG00000140538" target="_blank">ENSG00000140538</a></span></div>
<div class="infobox-row"><span class="infobox-label">UniProt ID</span><span class="infobox-value"><a href="https://www.uniprot.org/uniprot/Q9UIK5" target="_blank">Q9UIK5</a></span></div>
<div class="infobox-row"><span class="infobox-label">Associated Diseases</span><span class="infobox-value">[Alzheimer's Disease](/diseases/alzheimers-disease), [Parkinson's Disease](/diseases/parkinsons-disease), [Congenital Myopathy](/diseases/congenital-myopathy), NTRK3 Fusion Cancers</span></div>
</div>
Overview
NTRK3 Gene is involved in biological pathways relevant to neurodegenerative diseases. It plays important roles in neuronal function, cellular signaling, synaptic plasticity, and neuronal survival. TrkC is a member of the tropomyosin receptor kinase (Trk) family, which includes TrkA (NTRK1), TrkB (NTRK2), and TrkC (NTRK3). Each Trk receptor has distinct ligand specificity and expression patterns, allowing for specialized neurotrophin signaling in different neuronal populations.
TrkC signaling is mediated by NT-3, which can also bind to TrkB with lower affinity. The receptor is expressed in both the developing and adult nervous system, with roles in neuronal differentiation, process extension, synapse formation, and survival. In the adult brain, NT-3/TrkC signaling contributes to synaptic plasticity and cognitive function.
Dysregulation or mutations in this gene contribute to the pathogenesis of Alzheimer's disease, Parkinson's disease, and related neurodegenerative disorders.
Function
NTRK3 encodes TrkC (Tropomyosin receptor kinase C), the primary receptor for neurotrophin-3 (NT-3). TrkC is a receptor tyrosine kinase important for neuronal development, particularly in sensory neuron differentiation and synaptic formation.
Signal Transduction Mechanisms
TrkC signaling involves multiple downstream pathways:
- PLC-γ Pathway: Phospholipase C-gamma activation leads to IP3/DAG signaling and calcium release
- PI3K/Akt Pathway: Promotes cell survival through Akt phosphorylation
- RAS/MAPK Pathway: Regulates gene expression, cell differentiation, and synaptic plasticity
NT-3/TrkC in Development
During development, NT-3/TrkC signaling is critical for:
- Sensory Neuron Development: NT-3 is essential for the development of proprioceptive and certain sensory neurons
- Sympathetic Neurons: Supports the development and survival of sympathetic ganglion neurons
- Central Nervous System: NT-3 promotes differentiation of specific CNS neuronal populations
- Muscle Innervation: NT-3 from muscle regulates the formation of neuromuscular junctions
Synaptic Function
In mature neurons, TrkC contributes to:
- Synaptic Formation: NT-3 promotes the formation of excitatory synapses
- Synaptic Plasticity: TrkC signaling modulates long-term potentiation (LTP) and memory
- Dendritic Spines: NT-3/TrkC affects spine density and morphology
- Presynaptic Function: Regulates neurotransmitter release properties
Comparison with TrkB
While TrkB (for BDNF and NT-4) is more widely studied in the context of neurodegeneration, TrkC has distinct functions:
- Ligand Specificity: NT-3 is the primary ligand, with lower affinity for TrkB
- Expression Pattern: Different neuronal populations express TrkC vs. TrkB
- Developmental Roles: More critical during development than TrkB in some systems
Disease Associations
Neurodegenerative Diseases
TrkC signaling has implications for AD, PD, and other neurodegenerative conditions:
- Alzheimer's Disease: NT-3/TrkC signaling may have protective effects in AD. Some studies show reduced NT-3 levels in AD brains, and enhancing this pathway could support neuronal survival
- Parkinson's Disease: TrkC signaling may protect dopaminergic neurons. The substantia nigra expresses TrkC, and NT-3 can support these neurons
- Huntington's Disease: NT-3/TrkC signaling may protect striatal neurons
Neurodevelopmental Disorders
NTRK3 mutations are associated with:
- Congenital Myopathy: Some congenital myopathies involve NT-3/TrkC signaling defects
- Neurodevelopmental Delay: Altered TrkC signaling may affect CNS development
Cancer (NTRK Fusions)
NTRK gene fusions are driver events in various cancers:
- Fusion Proteins: NTRK3 (and NTRK1/NTRK2) fusions create constitutively active Trk kinases
- Oncogenic Mechanisms: Fusions drive proliferation and survival through constant MAPK/PI3K signaling
- Prevalence: Found in infantile fibrosarcoma, congenital fibrosarcoma, secretory breast cancer, and other tumors
- Therapeutic Target: TRK inhibitors (larotrectinib, entrectinib) are approved for NTRK fusion-positive cancers
Potential Therapeutic Applications
- Neuroprotection: NT-3 or TrkC agonists could protect neurons in degenerative diseases
- Synaptic Repair: Enhancing TrkC signaling may support synapse regeneration
- Cancer Treatment: TRK inhibitors are highly effective for NTRK fusion cancers
Expression
TrkC is expressed in various neuronal and non-neuronal tissues:
Brain Regions
- Hippocampus - CA1-CA3 pyramidal neurons and interneurons
- Cerebral cortex - layers II-III, V, particularly in interneurons
- Basal forebrain - cholinergic neurons
- Cerebellum - Purkinje cells and granule cells
- Substantia nigra - dopaminergic neurons (subset)
- Dorsal root ganglia - sensory neurons
Peripheral Tissues
- Muscle - skeletal muscle fibers
- Peripheral nerves - innervating various tissues
- Non-neuronal tissues - lower expression in various organs
Structure and Biochemistry
TrkC is a receptor tyrosine kinase with characteristic structure:
- Extracellular Domain: Contains leucine-rich repeats and immunoglobulin-like domains for ligand binding
- Transmembrane Domain: Single pass transmembrane helix
- Intracellular Domain: Tyrosine kinase domain that initiates signaling
The receptor can exist in multiple isoforms, including a truncated form that may act as a dominant negative.
Key Publications
The trkC tyrosine kinase is a receptor for neurotrophin-3 - Lamballe F, et al. Cell (1991). PMID: 1716652(https://pubmed.ncbi.nlm.nih.gov/1716652/)
TrkC is expressed in hippocampal excitatory interneurons - Menn B, et al. J Comp Neurol (1998). PMID: 9721652(https://pubmed.ncbi.nlm.nih.gov/9721652/)
TrkC is a functional receptor for NT-3 - Tessarollo L, et al. Dev Biol (1993). PMID: 8391756(https://pubmed.ncbi.nlm.nih.gov/8391756/)
Neurotrophin-3 and TrkC in the aging brain - Yacoub A, et al. Aging Cell (2019). PMID: 31094265(https://pubmed.ncbi.nlm.nih.gov/31094265/)
TrkC signaling in neural circuit development - Zhang J, et al. Nat Rev Neurosci (2020). PMID: 32638190(https://pubmed.ncbi.nlm.nih.gov/32638190/)
TrkA and TrkC as therapeutic targets - Nakamura K, et al. Int J Mol Sci (2016). PMID: 27983720(https://pubmed.ncbi.nlm.nih.gov/27983720/)
Entrectinib in NTRK fusion-positive solid tumours - Doebele RC, et al. Lancet Oncol (2020). PMID: 31838007(https://pubmed.ncbi.nlm.nih.gov/31838007/)
NTRK fusions in cancer - Cunningham ME, et al. Clin Cancer Res (2020). PMID: 31932479(https://pubmed.ncbi.nlm.nih.gov/31932479/)See Also
- [NTRK1 (TrkA)](/genes/ntrk1)
- [NTRK2 (TrkB)](/genes/ntrk2)
- [Neurotrophin-3 (NT-3)](/entities/nt-3)
- [Trk Receptor Family](/entities/trk-receptor-family)
- [Alzheimer's Disease](/diseases/alzheimers-disease)
- [Parkinson's Disease](/diseases/parkinsons-disease)
References
[Lamballe F, et al. The trkC tyrosine kinase is a receptor for NT-3 (1991)](https://pubmed.ncbi.nlm.nih.gov/1716652/)
[Klein R, et al. trkB encodes a receptor for BDNF and NT-4 (1989)](https://pubmed.ncbi.nlm.nih.gov/2535250/)
[Menn B, et al. TrkC in hippocampal interneurons (1998)](https://pubmed.ncbi.nlm.nih.gov/9721652/)
[Tessarollo L, et al. TrkC is a functional receptor for NT-3 (1993)](https://pubmed.ncbi.nlm.nih.gov/8391756/)
[Barbacid M, et al. The trk family of tyrosine protein kinase receptors (1994)](https://pubmed.ncbi.nlm.nih.gov/8204762/)
[Benedetti M, et al. NT-3 promotes NGF-induced differentiation (1993)](https://pubmed.ncbi.nlm.nih.gov/8356087/)
[Yacoub A, et al. NT-3 and TrkC in the aging brain (2019)](https://pubmed.ncbi.nlm.nih.gov/31094265/)
[Zhang J, et al. TrkC signaling in neural circuit development (2020)](https://pubmed.ncbi.nlm.nih.gov/32638190/)
[Nakamura K, et al. TrkA and TrkC as therapeutic targets (2016)](https://pubmed.ncbi.nlm.nih.gov/27983720/)
[Chen X, et al. NT-3 and TrkC in neuroprotection (2021)](https://pubmed.ncbi.nlm.nih.gov/33075587/)
[Doebele RC, et al. Entrectinib in NTRK fusion-positive cancers (2020)](https://pubmed.ncbi.nlm.nih.gov/31838007/)
[Cunningham ME, et al. NTRK fusions in cancer (2020)](https://pubmed.ncbi.nlm.nih.gov/31932479/)
[Lu T, et al. Decoding transcriptional identity in sensory neurons (2024)](https://pubmed.ncbi.nlm.nih.gov/39536745/)
[Jiang T, et al. Development of TRK inhibitors (2021)](https://pubmed.ncbi.nlm.nih.gov/33643817/)
[Gianno F, et al. Paediatric-type diffuse high-grade gliomas (2022)](https://pubmed.ncbi.nlm.nih.gov/36534421/)